Just wondering besides the Y-pipe being larger diameter, would it bolt up and be aligned still on a N/A as a catback?

 

it should fit the RB front exhuast fine but RB is notorious for making exhaust only fit as their complete system. the mating flanges are not in the same location as the OEM exhaust. so if you're trying to bolt it up to something else you will probably need to move the flanges.

 

Sorry bit exhausted but are you saying that the cat probably won't mate with the Y-pipes flange but as far as the hangars and such should be the same position?

 

the hangars match with the OEM hangar positions, yes. the flange to mate with the cat will probably be too short since the RB pre-silencers are longer than the OE cat length so the cat to catback will likely be too short.

someone can correct me if i am wrong. most of the cars i worked on had complete RB systems so i just mentally noted the differences.

 

Unfortunately I bought it a long time ago just the Y-pipe to exhaust without research so that's why I'm in the predicament I am in now. Would it be better to just have the Y-pipe cut and extended to fit or just have one fabbed up? Asking assuming you might have an idea cost wise for both. Thanks for your input.

 

a muffler shop could make the modifications for under $100, probably more like $40-50. ask them if they prefer having the exhaust hung prior or off the car to chop the flange off first.

 

Since the Y pipe is probably shorter, I would rather have the exhaust shop fabricate a bridge/adapter/connector pipe from the main cat (or pre silencer) to the Y pipe.

 

the difference is generally only a few inches so a bridge wouldn't be ideal. if you want to keep the catback unmolested and the cat is aftermarket then it might be a better source to lengthen.

 

How much would it be to fabricate a new Y-pipe just out of curiosity? I'm thinking resale value of the RB + pipe for future wise or do RB exhausts not go for too much anymore?

 

The y-pipe to main cat connection should not be in a different place from stock. I used an RB TII catback with stock precats/main cat on my car for awhile. The difference in flange placement comes into play when you want to use their presilencer with any non-RB downpipe or precats, etc... They are 3" longer than the main cat, but it's in the direction of the engine.

 

It's the rev model though not catback. Would that make any difference?

 

Ah, I missed that bit. The Rev II version looks like it has some length problems if not used as a complete system.

RX7 1986-1992: Exhaust - Complete Systems: REV TII Exhaust System - 87-91 TURBO II -

Judging from the placement of the hangars on the pre-silencer, the Rev II y-pipe is quite a bit shorter on the "cat side". On the standard RB catbacks, the metal hangars for the rubber donuts are mounted on a plate that bolts up at the presilencer/main cat-to-y-pipe junction.

 

Let me simplify the answer.



No.



Different size flanges, bolt and bolt holes won't line up.

Different length Y-pipe through exhaust cans than NA.

Now if you had a RB 2 1/2 inch y-pipe and can set up, would cat back line up perfectly.

The RevII was meant to be a complete system, not something you could shoehorn into an existing exhaust set up. That said, it has been done with the before mentioned fabrication. But I wouldn't recommend it.

 

What reason would you not recommend having the RB Y-pipe fabbed? I'm considering just having a Y-pipe fabricated from scratch in 2 1/2 as well. Also isn't the RB exhaust can inlet piping different length as well from the Rev II so having the RB catback Y-pipe would not work as well?

 

Ignore that last bit. I misread your message Hozz.

 

Save for the size of the larger inlet mounting flange and pipe, the dynamics of the exhaust cans are essentially identical to the cans on a RB 2 1/2" cat back. The real issue is that the length of the REVII Ypipe through exhaust cans are shorter than the RB 2 1/2" Ypipe through cans. What I'd do is have an adaptor fab'd up to fill the gap that would have a reducer end that mates to the 2 1/2" Cat flange and a 3" flange on the other end.

Hope it all works out for you.